A method for compensating the output of an angular position sensor assembly includes placing a first magnetic field sensor such that it is oriented ninety degrees from a second magnetic field sensor. A magnet is placed so that it is equidistant from the sensors. The magnet is rotated, and as it rotates, the signals output by the sensors are sinusoidal waves that are out of phase with each other by ninety degrees (90°C). Accordingly, the signals can be squared and summed to determined a temperature compensation signal.
|
1. A method for temperature compensating the output of an angular position sensor comprising the acts of:
providing at least two magnetic field sensors; placing a magnet equidistant from the sensors; rotating the magnet; receiving outputs from the sensors; and based on the output from the sensors generating a compensation signal, the compensation signal being generated by determining the square root of the sum of the squares of the outputs.
5. An angular position sensor assembly comprising:
a magnet; at least a first sensor placed in proximity to the magnet, the first sensor providing at least a first output signal; at least a second sensor placed in proximity to the magnet, the second sensor providing at least a second output signal that is ninety degrees out of phase with the first output signal; and a processor receiving the output signals, the processor including logic means for generating a temperature compensation signal in response to the output signals, the compensation signal being generated by determining the square root of the sum of the squares of the outputs.
2. The method of
sending the compensation signal to a control system.
6. The angular position sensor assembly of
7. The angular position sensor assembly of
|
The present invention relates to angular position sensors.
Power assisted steering is a standard motor vehicle equipment feature. It happens that in order for a typical power steering control system to properly operate, a steering column torque sensor must be included in the system to close the control loop. Torque sensors, such as resistance strip/strain gauge sensors, capacitance sensors, eddy-current sensors, magneto-elastic sensors, and transformer/strain gauge sensors, have been provided to determine the torque on the steering column. However, these sensors lack the sensitivity required for many of the present power steering control systems. Moreover, these sensors are extremely sensitive to changes in temperature and have limited durability.
Because of the high durability requirement, non-contact sensing technology is utilized. A typical non-contact sensor includes one or more magnetic field sensors, e.g., magnetoresistive sensors or Hall effect sensors, placed in proximity to a magnet, e.g., permanent or electrical. An electrical magnet provides constant magnetic field strength, but requires additional electronics that increase costs and the likelihood of sensor failure. On the other hand, a permanent magnet is simpler and more cost effective, but the field strength is very temperature dependent and can degrade over time.
The present invention understands that in order to compensate for temperature effects and degradation effects, linear Hall sensors can be used. Moreover, the present invention understands that a linear Hall sensor can be programmed with a temperature coefficient to match the temperature coefficient of a corresponding permanent magnet in order to compensate the sensor output for any effects caused by changes in temperature. Unfortunately, due to material variations in permanent magnets, programming a Hall sensor with a static temperature coefficient can result in the limited accuracy of the, e.g., angular position sensor in which the Hall sensor/permanent magnet configuration is used.
The present invention has recognized the above-mentioned prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.
A method for temperature compensating the output of an angular position sensor includes providing at least two magnetic field sensors. A magnet is placed so that it is equidistant from the sensors. Thereafter, the magnet is rotated and outputs from the sensors are received. Based on the output from the sensors, a compensation signal is generated.
In a preferred embodiment, the compensation signal is sent to a control system. Preferably, the outputs of the sensors are ninety degrees out of phase with each other. In a preferred embodiment of the present invention, the compensation signal is generated by determining the square root of the sum of the squares of the outputs.
In another aspect of the present invention, an angular position sensor assembly includes a magnet. A first sensor and a second sensor are placed in proximity to the magnet. The first sensor provides a first output signal and the second sensor provides a second output signal that is ninety degrees out of phase with the first output signal. In this aspect of the present invention, a processor receives the output signals and generates a temperature compensation signal in response thereto.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring initially to
As intended by the present invention, as the magnet 20 rotates, the outputs from the sensor 12, 14 are sinusoidal waves that are out of phase with each other by ninety degrees (90°C). As such, it can be considered that the waveform from one sensor, e.g., the first sensor 12, is a sine wave and the waveform from the remaining sensor, i.e., the second sensor 14 is a cosine wave. Moreover, since the change in magnetic field strength due to change in temperature affects both sensors 12, 14, the relative change due to temperature in amplitudes of the waveforms output by each sensor 12, 14 is the same. The sine and cosine waveforms have the following relationship:
Where:
A=field strength amplitude, and
X=measurement angle.
Referring now to
Alternatively, the instructions may be contained on a data storage device with a computer readable medium, such as a computer diskette having a data storage medium holding computer program code elements. Or, the instructions may be stored on a DASD array, magnetic tape, conventional hard disk drive, electronic read-only memory, optical storage device, or other appropriate data storage device. In an illustrative embodiment of the invention, the computer executable instructions may be lines of compiled C++ compatible code. As yet another equivalent alternative, the logic can be embedded in an application specific integrated circuit (ASIC) chip or other electronic circuitry.
Referring now to
With the configuration of structure described above, it is to be appreciated that the method to compensate the output of an angular position sensor provides a method that can be employed to dynamically compensate the output of an angular position sensor for effects caused by temperature and degradation.
While the particular METHOD TO COMPENSATE THE OUTPUT OF AN ANGULAR POSITION SENSOR as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it is to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. section 112, sixth paragraph, unless the element is expressly recited using the phrase "means for."
Lin, Yingjie, Nicholson, Warren Baxter, Aguinaga, Esau
Patent | Priority | Assignee | Title |
6774642, | Aug 27 2002 | Delphi Technologies, Inc. | Capacitive angular position sensor |
6836111, | Apr 03 2003 | Delphi Technologies, Inc. | Sensor assembly with a universal sensor module for sensing angular position of an object |
6873151, | Jul 08 2003 | Delphi Technologies, Inc. | Sensor assembly for sensing angular position |
6940275, | Dec 15 2003 | SENSATA TECHNOLOGIES, INC | Magnetic position sensor apparatus and method |
6946832, | Mar 27 2003 | Delphi Technologies, Inc. | Speed and angular position sensing assembly |
7023201, | Dec 15 2003 | SENSATA TECHNOLOGIES, INC | Magnetic position sensor apparatus and method |
7049808, | Mar 03 2004 | Delphi Technologies, Inc. | Apparatus for sensing angular position |
7181984, | Dec 31 2003 | TAIGENE METAL INDUSTRY CO , LTD | Magnetic sensor |
9080896, | Sep 24 2009 | Vitesco Technologies GMBH | Method for analyzing signals from an angle sensor |
Patent | Priority | Assignee | Title |
3728565, | |||
4746859, | Dec 22 1986 | Sundstrand Corporation | Power and temperature independent magnetic position sensor for a rotor |
4868497, | Nov 10 1986 | VDO Adolf Schindling AG | Determining angular velocity from two quadrature signals by squaring the derivative of each signal and taking the square root of the sum |
5130650, | Mar 20 1990 | TORRINGTON COMPANY, THE, A CORP OF DE | Bearing with a magnetic field angular position sensor |
5789917, | Dec 05 1990 | Moving Magnet Technologie SA | Magnetic position sensor with hall probe formed in an air gap of a stator |
6201389, | Apr 23 1997 | AB Eletronik GmbH | Device for determining the angular position of a rotating shaft |
6229299, | Nov 17 1998 | Caterpillar Inc.; Caterpillar Inc | System and method for computing the angular velocity and direction of a rotational body |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Aug 25 2000 | LIN, YINGJIE | Delphi Technologies, Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011223 | /0349 | |
Aug 25 2000 | NICHOLSON, WARREN BAXTER | Delphi Technologies, Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011223 | /0349 | |
Aug 25 2000 | AGUINAGA, ESAU | Delphi Technologies, Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011223 | /0349 | |
Sep 14 2000 | Delphi Technologies, Inc. | (assignment on the face of the patent) | / |
Date | Maintenance Fee Events |
Oct 27 2006 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
Dec 27 2010 | REM: Maintenance Fee Reminder Mailed. |
May 20 2011 | EXP: Patent Expired for Failure to Pay Maintenance Fees. |
Date | Maintenance Schedule |
May 20 2006 | 4 years fee payment window open |
Nov 20 2006 | 6 months grace period start (w surcharge) |
May 20 2007 | patent expiry (for year 4) |
May 20 2009 | 2 years to revive unintentionally abandoned end. (for year 4) |
May 20 2010 | 8 years fee payment window open |
Nov 20 2010 | 6 months grace period start (w surcharge) |
May 20 2011 | patent expiry (for year 8) |
May 20 2013 | 2 years to revive unintentionally abandoned end. (for year 8) |
May 20 2014 | 12 years fee payment window open |
Nov 20 2014 | 6 months grace period start (w surcharge) |
May 20 2015 | patent expiry (for year 12) |
May 20 2017 | 2 years to revive unintentionally abandoned end. (for year 12) |